Ammunition priming mixture and compound therefor



Patented Sept. 21, 1954 AIWMUNITION PRIMING MIXTURE AND' COMPOUND THEREFOR JosephF. Kenney, Bridgeport, Conn., assignor to Remington Arms Company, Inc., Bridgeport, Conn., a corporation of Delaware No Drawing. Application November 22, 1950, Serial No. 197,179

3' Claims.

This invention relates to a novel composition of matter, and to the use of such composition as an ingredient of deflagrating compositions, particularly ammunition priming mixtures.

The conventional ammunition priming mixture comprises an oxygen-yielding substance or oxidizer, an oxygen-deficient substance or fuel adapted to combine with oxygen supplied by the oxidizer with the evolution of substantial heat and flame, a percussion-sensitive ingredient adapted to decompose under impact, and an explosive activated by and in conjunction with the percussion-sensitive material, generating sufficient heat and pressure to initiate the reaction between fuel and oxidizer.

As more fully appears hereinafter, mixtures for rimfire cartridges usually contain, in addition to the above reacting ingredients and as an aid to initiating their reaction, an inert abrasive, such as ground glass. The essential reaction is the combustion of the fuel by the oxidizer, and

all ingredients other than the fuel and the oxidizer may be regarded as combustion promoters.

The novel compound contemplated by this invention is frictionand percussion-sensitive, and is deficient in oxygen, so that in ammunition priming it is capable of serving the dual purpose of either or both combustion initiator and fuel. Moreover, it decomposes under impact at such a rate and with such energy that it is capable of functioning as the sole explosive ingredient.

The novel compound is a complex or double iron salt of styphnic acid and hypophosphorous acid, apparently containing ferric styphnate and ferric hypophosphite in the proportions of 1-to-4, its composition being This compound may be prepared as follows: 5 grams of styphnic acid and 082 gram of magnesium oxide are dissolved in about 100 cc. of water-the dissolved substances react to form about 5.4 grams of magnesium styphnate of the composition:

CeH(NO2 aOzMg To this, while stirring, is added 15 grams of ferric nitrate and the stirring is continued until solution is effected. To this solution there is added slowly a solution of about 8.6 grams of sodium hypophosphite in 50 cc. of water, the addition being completed in about minutes. The reaction is preferably carried out at room temperature, but may be performed at any temperature between about 0 C. and 60 C. There is recip itated a light brown amorphous material which contains about 18% iron and about 20% phosphorus, these figures very closely approaching the theoretical iron and phosphorus content respectively of ferric styphnate-ferric hypophosphite of the formula given above. It has an apparent density of 0.51 gram per cubic centimeter. Its sensitivity to static electricity, as measured by the discharge of a 300 mmf. capacitor, is 50% fires at 500 volts, and 100% fires at 1000 volts. On a temperature gradient bar it explodes instantaneously at 250 C. in 2 seconds at 240 C.; and in about 5 seconds at 230 C. In admixture with 10% glass, the free fall of a 2-ounce weight produces fires at and fires at 1".

The new compound may be used in conjunction with very numerous combinations of known oxidizers and/or fuels and/or explosives. Typical ammunition priming compositions in which ferric styphnate-ferric hypophosphite functions as a percussion-sensitive ingredient, replacing such a material as tetrazene, are as follows:

Range, Preferred,

Percent Percent Ferric Styphnate-Ferric Hypophosphite.. 2-25 4 Normal Lead Styphnate 25-45 38 Barium Nitrate 2040 25 Glass 20-40 33 Range, Preferred,

Percent Percent Ferric Styphnate-Ferric Hypophosphite." 2-25 5 Normal Lead Styphnate 25-50 41 Tetrazene l- 5 4 Barium Nitrate 40-65 50 This mixture has an average sensitivity with a 2- oz. weight of 6.52" and a standard deviation of 0.76". The low value for standard deviation is particularly desirable, being only about half that found in comparable mixtures depending upon an abrasive to reach a satisfactory sensitivity level.

Conventional priming mixtures, particularly those of the non-corrosive type, almost invariably contain lead, mercury or other heavy metal compounds, such as the lead styphnate included in the compositions above-mentioned, the decomposition of which leaves toxic residues which are undesirable, particularly when fired indoors. The use of ferric styphnate-ferric hypophosphite has been found to enable the production of non-corrosive priming compositions which are entirely free of lead and other toxic compounds. The use of such priming compositions in cartridges containing lead-free projectiles enables the manufacture of complete cartridges which are nontoxic and thus safe and desirable for use in confined spaces, such as various types of indoor ranges. Typical priming compositions of this group are the following:

Range, Preferred, Percent Percent Ferric Styphnate-Ferric Hypophosphite.-. 25-50 40 Barium Nitrate 20-40 25 Glass 20-40 35 Compositions of this group are especially sensitive to percussion, the preferred as given above 4 having an average sensitivity with a 2-02. weight of 1.55" with a, standard deviation of 0.92".

What is claimed is: 1. The composition of matter, ferric styphnateferric hypophosphite.

2. An ammunition priming composition consisting essentially of- 3. An ammunition priming composition consisting essentially of- Per cent Ferric styphnate-ferric hypophosphite 5 Normal lead styphnate 41 Tetrazene 4 Barium nitrate 50 References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,132,996 Palmieri Oct. 11, 1938 2,202,647 Brun May 28, 1940 2,292,956 McNutt Aug. 11, 1942 

1. THE COMPOSITON OF MATTER, FERRIC STYPHANATEFERRIC HYPOPHOSPHITE.
 2. AN AMMUNITION PRIMING COMPOSITION CONSISTING ESSENTIALLY O 